Add IRenderMime interface and modernize RenderMime.
Add IRenderMime interface and modernize RenderMime.

jupyter/jupyterlab,TypeFox/jupyterlab,jupyter/jupyterlab,eskirk/jupyterlab,charnpreetsingh185/jupyterlab,jupyter/jupyterlab,jupyter/jupyterlab,eskirk/jupyterlab,eskirk/jupyterlab,TypeFox/jupyterlab,jupyter/jupyterlab,TypeFox/jupyterlab,charnpreetsingh185/jupyterlab,eskirk/jupyterlab,TypeFox/jupyterlab,charnpreetsingh185/jupyterlab,charnpreetsingh185/jupyterlab,eskirk/jupyterlab,TypeFox/jupyterlab,charnpreetsingh185/jupyterlab